Pyroxylin compound



JOHN II. STEVENS, OE NEWARK, NEW JERSEY, ASSIGNOR TO THE OELLULOID COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

pvsoxvun COMPOUND.

SPECIFICATION forming part of Letters Patent No. 608,726, dated August 9, 1898. Application filed April 1, 1898. Serial No. 676,056. (No specimens.)

To all, whom it may concern,- V

Be it known that I, JOHN H. STEVENS, of the city of Newark, county of Essex, and State of New Jersey, have invented certain new and useful Improvements in Pyroxylin Gompounds, of which the following is a specification The object of my invention is to render pyroxylin or nitrated cellulose and its compounds less liable to acid decomposition. As is well known, the nitro elements in perfectly pure or freshly-made pyroxylin are held in such close chemical combination that it is neutral to test-paper. I In the course of time and under extraordinary conditions-like high temperatures, for instance-these nitro elements are slowly evolved as free acid, which results in great danger when the dry pyroxylin is stored or transported and also injures those compounds which are made by dissolving pyroxylin for the purpose of making liquid solutions or solid products.

I have discovered that by combining pyroxylin with asmall proportion of lead acetate this tendency to a disorganization of its constituent elements is entirely prevented under ordinary conditions and is minimized under extraordinary conditions,lik'e prolonged heat mg or age.

In practicing my invention I proceed as follows: IVhen the pyroxylin is to be sold or stored in a dry state, I introduce the lead acetate by thoroughly wetting the pyroxylin with a solution of the preservingsalt in water or other menstruum which does not dissolve the pyroxylin. On evaporating or otherwise removing the water the pyroxylin is left in a more permanent condition.

In using the acetate of lead in pyroxylin compounds made with solvents I preferably introduce the acetate of lead dissolved in wood-spirit or grain-alcohol. The acetate of lead is especially suitable for materials used as explosives or pyroxylin compounds in which extreme paleness is not a necessary feature. I have, however, obtained good results byits use in a pyroxylin compound made in imitation of clear tortoiseshell and have success fully employed it in making thin trans= parent sheets. The slightly-yellow color imparted by the acetate of lead does no harm to many of these transparent products.

By. transparent products I mean those solid homogeneous combinations which per mit the transmission of light-for instance,

imitations of glass, amber, shell, &c.-and also solutions and varnishes used for pro tective purposes. Explosives, like guncotton and smokeless powder, are not classed with transparent compounds, as their form prevents theunimpeded passage of light. Be

sides, transparency in explosives is not at all required.

Acetate of lead is also useful in making an imitation of jet from pyroxylin, as theeffects of the salt do not interfere with the required depth of color, while the desirable depth of color or intense blackness is interfered with more or less when some of the ordinary antacid substances-like magnesium carbonate, for instance are used.

As to proportions, for explosive compounds I would recommend two per cent. by weight,

of the salt to the amount of pyroxylin pres ent in the compound. For manufacturing compounds made with solvents I have obtained the best results by the use of one per cent.

Although I have only spoken of lead acetate thus far, yet lead acetate is only one member of a class of substances known as the lead salts of the volatile monatomic fatty acids. These acids are formic, acetic, propionic, butyric, and Valerie acids. Ihave found that all of these salts are equivalents as preserving agents for pyroxylin, although they vary in intensity of effect. The lead acetate is to be preferred, both on account of its gen eral properties and low price.

The butyrate and valerate of lead are equal to the acetate as preservers and can be used in the same proportions; but they have an ofiensive odor. The propionate of lead is a powerful antacid and also yields transparent products. The formate of lead is more feeble in preserving power than the acetate and other members of this class, and 1t does not give good transparency.

Eflicient antacid or preserving agents to be used with pyroxylin are scarce. Many substances have been proposed and used, but with more or less failure. I have found in practice that some of the proposed antacids really aid decomposition and seem to either invite the nitro elements to leave the pyroxylin or else by their presence or reducing action change the pyroxylin to a more easily decomposable condition.

.In general I advise using the lead acetate and lead propionate in a proportion of one per cent, by weight, of the salt to the pyroxylin for transparent products and in non-ex plosive compounds and would recommend the use of both of these salts and the formate in a two-per-cent. proportion for explosive compounds. I would confine the butyrate and valerate of lead to explosives or to compounds in which the offensive odor they impart would be unobj ectionable. I do not confine myself to definite proportions; but the proportions suggested are the best to use.

I am unable to explain why the lead salts 'act as a preserving agent when the lead is already saturated with an acid and in neutral condition, as is the case with lead acetate. I can only saythat my experiments show this to be a fact.

I have found that in the case of salts containing two or more dissimilar acid radicals the preserving power depends largely on the nature of the acid radicals present. Thus a compound lead salt containing the radical of acetic acid would have some preserving power even though the other acid radical present possessed no power to form an antacid of pyroxylin and a lead salt of a volatile monatomic fatty acid.

2. A new composition of matter consisting of pyroxylin, a solvent of the same, and a lead salt of a volatile monatomic fatty acid.

3. A new transparent composition of matter containing pyroxylin and acetate of lead.

JOHN H. STEVENS.

Witnesses ABRAHAM MANNERS, J. W. FAITONTE. 

